It’s a rite of passage for adolescents, and a stubbornly challenging medical problem. Acne affects millions, but the best treatments for it — antibiotics that target the bacteria that cause zits — are losing potency because of increasing drug resistance.

Now scientists at the University of California, Los Angeles, suggest a potential new weapon against problem skin: harmless viruses that are already living in our pores. These viruses, known as phages, naturally kill the bacterium Propionibacterium acnes, which is the primary culprit of acne. By boosting the phages’ power, the researchers say acne could be brought under control.

Under normal circumstances, P. acnes lives happily in the pores of the skin, along with hair follicles and oil glands that produce sebum to keep the skin and hair from drying out. Acne erupts when the oil glands produce too much sebum, clogging the pore. Then bacteria build up, and the immune system decides to react against them, launching an attack that leads to inflammation and production of the pus-like substance that emerges as a pimple.

Puberty is associated with an explosion in the P. acnes population, with some teens harboring as much as 100 times more bacteria than adolescents without acne.

Laura Marinelli, a postdoctoral researcher in dermatology at UCLA, and her colleagues discovered the P. acnes-killing viruses by analyzing deposits from pore strips collected from volunteers. Within each pore, the researchers found, were a number of microbial residents, including P. acnes and its neighbors, such as phages. These are viruses that cannot replicate on their own, but need to attach themselves to another cell in order to hijack its reproductive machinery and generate more copies of itself.

Previous studies had identified certain phages that were associated with P. acnes, but Marinelli’s group used DNA sequencing techniques to better understand the genetic blueprint of the microbial universe in the pores and found a family of 11 phages that were specifically designed to target and kill P. acnes. These phages attach themselves to P. acnes bacterial cells and inject their DNA into the bacteria, turning them into phage factories. Once enough phage progeny are generated, the bacterial cell is destroyed, bursting open to release the phages. Generally, some P. acnes are already dying off this way, but because they outnumber the phages, there remains a higher concentration of pimple-causing microbes in the skin.

But, says Marinelli, “by potentially using phages, we can control bacteria in people with acne. It there is too much bacteria on the skin, we can bring their numbers down to healthy levels, so they wouldn’t be aggravating the immune system.”

Ideally, the phages would become part of a cream or topical treatment that acne-prone people would apply to the skin. Or, if researchers can isolate the proteins that the phages use to destroy the P. acnes bacteria, the cream could contain a concentrated form of those compounds.

The proper treatment of acne would still have to leave behind the right concentration of P. acnes, however. Marinelli says that because the bacteria also perform healthy functions, such as keeping the skin and body free of infection from other nasty microbes, any acne treatment shouldn’t eliminate P. acnes completely. But keeping its numbers in check could save millions of teens from the pain of pimply skin.